1. Field of the Invention
The invention relates generally to the field of oil and gas well services. More specifically, the present invention relates to an apparatus that provides positive indication of orientation of perforating guns disposed within a wellbore.
2. Description of Related Art
The orientation of perforating guns is the subject of many prior art patents. These patents include Daniel, U.S. Pat. No. 4,410,051, Kitney, U.S. Pat. No. 5,273,121, George, U.S. Pat. No. 4,637,478 and Edwards, U.S. Pat. No. 5,964,294. Orienting perforating guns in deviated wells enables the well operator to aim the shaped charges of the perforating gun at specific radial locations along the circumference of the wellbore. This is desired because the potential oil and gas producing zones of each specific well could exist at any radial position or region along the outer wellbore circumference. These potential producing zones around the deviated well dictate the desired orientation of a perforating gun to ensure that the shaped charges perforate the casing adjacent a potential producing zone.
Because perforating guns are often thousands of feet below the surface of the earth during the perforation process, it is difficult to determine if the perforating gun is in the desired orientation at the instant the shape chargers are detonated. Knowing the orientation of the perforation gun during detonation can be useful to the well operators. If the gun is not in the desired orientation, adjustments can be made to the tool so that it is properly oriented in subsequent operations. Alternatively, if the perforating gun was well out of the orientation tolerances when the well was perforated, the possibility exists of sand entering the wellbore. Having knowledge of potential sand production due to errant shaped charge position, the well operators could consider corrective action to address errant perforations. The corrective action includes gravel packing operations to curb any sand production and possibly shutting off the sand producing portion of the wellbore and drilling an alternative bore around that section. Because these operations are very expensive the well operators must have reliable evidence of perforation shot orientation before undertaking such corrective action. Accordingly there currently exists a need by which the actual orientation of the perforating gun can be readily discerned from a quick examination of the perforating gun after the perforation process.